Electric switch



Patented July 3, 1945 UNITEo STATES PATENT oFFlcE ELECTRIC SWITCH RobertW. Goff, Schenectady, N. Y., assigner to General Electric Company, acorporation New York Application April 15, 1944, Serial No. 531,220

, "z claims.

yMy invention relates to time element electric l switches and moreparticularly to multicontact entconnection `between the members and theaction of the air piston, the switch member moves in delayed followingrelation with the ./manually operable member. Within the casing andalong theside walls thereof there are mounted a plurality of contileverspring contacts having offset portions variablyfspaced along the'path ofmovement ofthe switch member.' The contacts y'are controlled by means ofcamming memcrane motor a plurality`V of motor starting contactorscontrolled by a plurality of time delay relays. These contactors andrelays are carried on' the trolley where space is limited. The timedelay relays are in turn controlled by forward and reverse push buttonscarried at the end of Such an arrangement is both I a pendant cable.bulky and expensive, due to the large number of time delay relaysincorporated in the control panel. Furthermore, it has been found inoperation that the use of push'buttons on the pendant cable permitsaccidental operation of the crane, as when the cable is allowed to swingfreely and the-push buttons are depressed by hitting against astationary object. y

In order to reduce the cost and'improve the "operation of floorcontrolled crane control systems, itis desirable to incorporate the timeelement of motor starting operation in the hand operated switch itself,and also to provide a pull type manual switch rather than a push buttontype.

Accordingly, it is a general object of my invention to provide a new andimproved manually operable time'delay control switch which shallbesimple and reliable in oper'ation and inexpensive to manufacture.

It is a more specific object of my invention to provide a time delaymotor starting control switch of the manually operable type having amultiplicity of sequentially actuated contacts.

Briefly, my invention comprises an enclosing casing having lsidewalls'and at least one end wall formed -to provide a re-entrant aircylinder. The movable switch member comprises a piston positioned withinthe cylinder and having an air bleeder valve to control the passage ofair past the piston. The switch member is resiliently connected to amanually operable member biased in one direction and slidably mountedwithin lthe casing-for movement against its bias by a handle arranged tobe pulled outwardly from the casing. Because of the resilibers pivotallymounted upon the switch member and interposed between the cantileversprings and a wall of the casing.

My invention will be more'fully understood and its objects andadvantages, further appreciated by referring ynow to 'the followingdetailed specification taken in conjunction with the accompanyingdrawing in which ljlgs'. 1 and 2 are side elevations, partlyiii/section, Aof an electric switch embodying my'invention; Fig. 3 is an,end `view of theswitch; Fig. 4 is an exploded perspective view of thesame switch, partly in section; and-Fig. 5 is a perspective view of thepiston control valve.

' Referring now to thedrawingfand particularly to Figs. 1, 2 and 4, Ihave shown a multicontact vtime element electric switch comprising anenclosing casing IIi'and removable cover II, a plurality 0f-pairs ofcooperable switch contacts I2,"

and a reciprocal operating handle I3. Preferably, the enclosing casingI0 and cover .II are formed'of a suitable molded plastic insulatingmaterial. The removable end wall or cover II is formed toprovide aninwardly extending or re-entrant cylinder I'Ia having a suitablemetallic liner IIb.. y

Positioned `within the enclosing casing I0 and in telescoping relationwith the stationary cyl`- inder IIa, I provide a movable cylinder I4slidably mounted and rigidly attached/ to the operatinghandle I3 by apair of studs I5. The sliding lcylinder Il and handle I3 are biasedtoward the bottom wall of the'casing I0 and against an f cylinder I4 fordelayed following movement with respect thereto, I provide a movableswitch member including a piston 20, a hollow piston stem Il, and a natplate 2| o! insulating material.

The lower end wall of the slidable cylinder Il is apertured at 2Iaslidably to accommodate the piston stem I3. The plate 2| is positionedbelow the cylinder Il and is rigidly connected, as by a screw thread, tothe piston stem I8. A helical compression spring 22 encircling the stemI8 is disposed between the piston and the lower end wall of the slidingcylinder Il thereby resiliently to connect the switch member to thesliding cylinder Il with the fiat plate 2| normally held against thebottom wall of the cylinder I4 and the piston stem I3 positionedcentrally within the cylinder Il to hold the piston 20 in the cylinderI3.

The hollow piston stem I 9 is provided internally with a variable air oriluid control valve 23. Referring Aparticularly to Figs. 1 and 5, itwill be observed that the valve 23 is cylindrical and provided at oneend with a threaded portion of enlarged diameter by means of which thevalve is variably positioned internally o! the hollow piston stem I3. Atits other end the valve 23 is provided with a longitudinal groove 2lincreasing in depth and width as it approaches the end of the valve. Thegroove 2l cooperates with the internal surface of the hollow stem I9 ltoprovide a variable air vent between the interior and exterior of thecylinder I3. This air bleeding passage is completed by a radial hole 25in the piston stem I9 and a hollow screw 28 used to hold in place apacking ring 21 carried by the piston head 20.

Referring now particularly to Figs. 2 and 4, it will be noted that eachpair of cooperating switch contacts I2includes a movable contact mountedupon the free end o1.' a cantilever contact spring III. The cantileversprings 30 are attached at one end to a side wall of the casing III andextend in substantially parallelspaced relation to the side wall fornearly the full length of the casing. Preferably, as shown at Fig. 2,the springs 30 are mounted upon a small boss 3| formed upon the casingwall in order to provide between the springs and the casing wallsuiiicient space for a camming member without producing excessivebending of the spring strip. It will be noted from Figs. 2 and 4 thateach cantilever spring strip 3I| is odset away from the side wall o! thecasing III, Vas at 30a. The offset portions 30a are variably spaced fromthe ilxed ends of the contact springs. These offset portions 30acooperate with camming members in the form of substantially rectangularstirrups 32 and 35 pivotaliy, attached to the fiat plate 2| and to themovable cylinderI I4, respectively. The stirrups 32 and 35 may be wireloops, and each has one rod-like end interposed between 4the casing walland the associated spring 30. Since the iiat plate 2| and the piston 20are rigidly connected and constitute a movable switch member, it will beevident that the camming stirrups 32 follow the movement ofthe piston2li.

While it is possible to provide any convenient number of contact springspositioned around the internal walls of the casing I0 in any desiredmanner, I have shown a preferred embodiment of my invention in whicheach of the two opposite side walls of the casing I0 between the wallshaving the bosses Iia is provided with three parallel cantilever contactsprings 30. Of these three springs, the two outer springs are arrangedfor cooperation with the camming stirrups 32 mounted upon the plate 2 I.To illustrate that at least one instantaneous contact member may beprovided in conjunction with a plurality of time element contacts, Ihave shown, particularly at Figs. 2 and 4, the contact camming stirrup35 positioned for cooperation with the central contact spring of eachgroup or three springs and pivotaliy mounted upon a projecting boss 38on the sliding cylinder Il. Thus, the stirrup 35 is moved directly bythe operating handle I3, while the stirrups 32 are moved by the delayedmovable switch member.

In operation, the switch contacts I2 are controlled, and moreparticularly are sequentially closed, by withdrawing the handle I3 fromits normal biased position in engagement with the casing cover II. Thehandle may be withdrawn quickly or slowly, and may be stopped at anyintermediate point between its extreme limits oi travel. The extent towhich the handle I3 is withdrawn determines extent of movement of theswitch member, and hence the number of switch contacts closed.

let it be assumed `for the purpose of illustration that the handle I3 iswithdrawn rapidly and to the limit of its outward movement. tion, theslidable outer cylinder I4 is immediately drawn upward into telescopingrelation with the stationary cylinder IIa against the bias of thecompression springs II. The piston 2|) and plate 2|, however, do notmove upward as rapidly as does the slidable cylinder I4, due to theentrapment oi air between the piston 20 and the upper end of thecylinder Iib. Accordingly, the piston 2l) is initially moved upwardlyonly far enough to compress the air in the cylinder I Ib sufficiently tobalance the force of the spring 22. The remainder of the upward movementof the handle I3 compressesthe spring 22 thereby to bias the piston 20upwardly. If the handle I3 is now held in its uppermost or retractedposition, the piston 20 gradually moves into the cylinder lib under theaction oi the spring 22 the enti-upped air escapes through the hollowbolt 2E, the valve 23, and the air vent 25. The speed ci this upwardmovement is controlled bythe size or the opening through the valveaperture 24. The size of this opening may be controlled by turning thethreaded portions of the needle valve farther into or farther out of thepiston stem I3. As the piston 20 moves upwardly at a predetermined speedcontrolled by the air valve, it carries with it the flat .plate 2| andthe camming stirrups 32. As the camming stirrups 32 move upwardly, theysequentially come into juxtaposition with the offset portions 30a of thecantilever contact springs 3U. As each camming stirrup 32 comes underthe associated offset spring portion 30a, the contact carried by thatspring closes.

It will be noted that, while the stirrups 32 are moved upwardly at aslow predetermined speed by the piston 20 and spring 22, the stirrup 35,being attached directly to the slidable outer cylinder I4, is movedupward instantaneously along with the operating handle I3.

While it will be understood that my invention does not necessarilyinclude an instantaneous contact actuated by the operating handle, thisarrangement has been chosen by way of illustration because of itssuitability to the kind of motor starting apparatus to which referencehas previously been made. In this connection it will be evident to thoseskilled in the art that the central instantaneous contacts I2 onopposite sides of the enclosing casing may be used as line switchesinstantaneously to connect a motor to a source of supply when theoperating handle I3 is withdrawn. The remaining spring contacts By suchactrue spirit and scope of my invention.

controlled by the piston may then be arranled i for sequential closureas the ilat plate 2| moves upwardly and connected gradually toshort-circuit a starting resistor in series circuit relation with themotor. In a typical application to traveling crane motor control, theusual three crane motors may each be provided with a forward and reversemotor starting control switch of the type described above. These sixswitches may be mounted one above the other, or in any other'desiredmanner, in a block carried at the end of a pendant cable. With switchesof this type, there is no danger that any of the crane motors will beinadvertently started by swinging of the control cable and the switchbox against an object. Collision of the switch handle I3 with. an objectcannot start the motors, since motor starting requires withdrawal ratherthan depression of the operating handle I3. Furthermore,

'it will be noted that the time delay necessary for reducing theresistance of the motor circuits is incorporated in the manuallyoperable cable switch itself, so that no time delay relays need beincluded on the motor contactor panel carried on the trolley. Many otherapplications of the invention will occur to those skilled in the art.

While I have described only a single preferred embodiment of myinvention by way of illustration, many modifications will occur tothoseskilled in the art, and I therefore wish to have it understood thatI intend in the appended claims to cover all such modications as fallwithin the What I claim as new and desire to secure by Letters Patent ofthe United States is:

l. A manually operable electric switch comprising a base, a cylinderiixedly attached to said base, a movable switch member vincluding apiston slidably positioned in said cylinder, a manually operable memberslidably mounted upon said base and resiliently connected to said switchmember, means for biasing said manually operable member in onedirection, a plurality of cantilever spring contacts mounted upon saidbase, and camming means interposed between said contacts and said baseand connected to said switch member to control said contacts inaccordance with movement of said piston.

2. A manually operable electric motor starting switch comprising anenclosing casing, a cylinder xedly atttached to and extending into saidcasing, a movable switch member including a piston slidably mounted insaid cylinder, a manually operable member slidably positioned in saidcasing and resiliently connected to said switch member, means forbiasing said manually operable member in one direction, aplurality ofcantilever spring contacts mounted upon an interior 'Wall of saidcasing, camming means interposed between at least one of said contactsand said wall and the other of sid contacts and said wall and connectedto said switch member to control said other contacts in accordance withmovement of said piston.

3. A manually operable electric switch comprising a base, a cylinderfixedly attached to said base, a movable switch member including a pisfdirection, said manually operable member being movable against its biasto bias said piston for movement in said cylinder at a speed controlledby said valve, a plurality oil cantilever spring contacts mounted uponsaid base in substantially parallel spaced relation with one surfacethereof, and camming means interposed between said spring contacts andsaid one surface and connected to said switch member sequentially tocontrol said contacts in accordance with movement of said piston.

4. A manually operable electric switch comprising an enclosing casinghavingside and end walls, said casing including a reentrant cylinderformed upon one of said end walls, a movable switch member including apiston slidably positioned in said cylinder, a fluid ilow control valvearranged to control the passage of air past said piston, a manuallyoperable member including a handle member resiliently connected to saidswitch member, means for biasing said manually operable member in onedirection, a plurality of cantilever spring contacts mounted upon saidside walls and extending in substantially parallel spaced relationthereto, and common means including a plurality of rods interposedbetween said spring contacts and said side walls and pivotally connectedto said switch member for se-'r connected to said manually operablemember; and additional camming means interposed 'between quentiallycontrolling said contacts in accordance with movement of said piston.

5. A manually operable electric switch comprising an enclosing casinghaving side and -end walls, said casing including a reentrant cylinderformed upon one of said end walls, a second cylinder slidably mountedwithin said` casing in external telescoping relation with said reentrantcylinder, a manually operable handle rigidly connected to said secondcylinder, means for biasing said second cylinder in one direction,amovable switch member including a piston slidably positioned in saidreentrant cylinder and resiliently connected to said second cylinder, afluid control valve arranged to control the passage of air past saidpiston, a plurality of cantilever spring contacts mounted upon said sidewalls and extending in substantially parallel spaced relation thereto,and camming means including a plurality of rods interposed between saidspring contacts and said side walls and pivotally connected to saidswitch member for sequentially controi-y ling said contacts inaccordance with movement of said piston.

6. A manually operable electric switch comprising tan enclosing casinghaving a substantially flat inner wall, a plurality of pairs ofcooperating switch contacts in said casing, a manually operable memberslidably mounted in said casing for movement in substantially parallelispaced relation to said wall, a movable switch member, time elementmeans `lconnecting said switch member to said manually operable memberin delayed following relation, a plurality of cantilever contact springsmounted upon said wall and extending in substantially parallel spacedrelation thereto to control said contacts, andy camming meansVinterposed between eachof said springs and said wall and pivotallymounted upon said switch member for actuating said contacts.

7. A manually operable electric switch comprising an enclosing casinghaving a substantially flat inner wall, a plurality of pair ofcooperating switch contacts in said casing, a manually operable memberslidably mounted in said casing ity of substantially rectangularstirrups each having one end pivotally mounted upon said switch memberand the opposite end interposed between said wall and one of saidcontact springs for camming cooperation with the offset portions of saidcontact springs to control said contacts.

ROBERT W. GOFF.

CERTIFICATE CF CO RREC TI ON.

Patent No. 2,5'9,70il.

July 5, 19ll5- ROBERT W. GOFF.

It is hereby certified that error appears in the printed specificationof the above .numb ered patent requiring correction as follows: Page l,second column, line 6, for "contilever" read cantilever; page 5, firstcolumn, line 51, for "atttached1 read --a ttached;` line 65, for "sid"read said; and. second column, line 25, for "common" read --camming--line 75, forv"pair" read .pairs; and that the said Letters Patent shouldbe read with this correction therein that the same may conform to therecord of me ease in the Patent office.

Signed and sealed iiiis 2nd day of' October, A. D. l9ii5.

(Seal) Leslie Frazer First Assistant Commissioner of Patents.

